MOSCOW (AP) -- Hollywood celebrity Hilary Swank said she "deeply regrets" visiting a concert held on the birthday of the Kremlin-backed Chechen leader, who is accused of torture, abductions and killings by human rights groups.

The two-time Oscar winner said that she was unaware of the disappearances, house torchings and extrajudicial killings reportedly orchestrated by Ramzan Kadyrov in the southern Russian republic.

"I deeply regret attending this event," Swank said in a written message to The Associated Press. "If I had a full understanding of what this event was apparently intended to be, I would never have gone."

Swank issued the message after the Human Rights Watch criticized her — along with Belgian actor Jean Claude Van Damme, singer Seal and British violinist Vanessa Mae — for attending a show that, it says, "trivializes the suffering of countless victims of human rights abuses."

On Kadyrov's 35th birthday on Oct. 5, his government organized a lavish concert in Chechnya's provincial capital, Grozny, a city that has been in the process of restoration after widespread destruction from two wars between Chechen separatists and Moscow since 1994.

The celebrities — as well as dozens of Russian politicians and pop stars — showed up to congratulate Kadyrov from a stage arranged between a gigantic mosque and a newly built business center. During the birthday show, Swank said that she had been taken by the Chechen government's "passion to make peace and to make something beautiful." She claimed in her apology that her invitation to the concert made no mention of Kadyrov's birthday.

Under Kadyrov's leadership, Chechnya has become relatively quiet, and the insurgent violence has largely migrated to neighboring republics of the volatile Caucasus region. Kadyrov is a former separatist rebel who has boasted of killing his first Russian soldier at age 15. He switched his alliance to the federal side at the start of the second Chechen war in 1999.

A string of Kadyrov's critics and political rivals have been brutally murdered in recent years in Russia, Austria and Dubai. Kadyrov has consistently denied involvement in any of the killings, saying the accusations are fabricated to blacken his name.

Swank won Oscars for her roles in "Boys Don't Cry" and "Million Dollar Baby." Her screen credits also include "Freedom Writers," "P.S. I Love You" and "Amelia."